My office has a new colleague join us a few months back. She appeared to be a lovely lady, or so I thought. She talks no stop to the point people in the office have started carrying on with their work whilst she talks and just nod their heads, to make it worse she repeats herself continuously. This is a little frustrating but I could handle it.

Recently she has started snapping and being sarcastic to me. I said nothing as I put it down to her being stressed I a new job. She carried on so I eventually said something when we were at the side of our office alone. I calmly told her that I was offended by how she had spoken to me and it's not been the first time she has done it. Well. She threw her arms around, cried, told me not to speak to her, shouted back. I was gobsmacked, she was like a child. I must add she is 20 years my senior, but was acting 12.

This continued for 10 mins until others came in and she eventually asked to go into an office with a supervisor. An hour later she emerged and said she apologised if she was rude, but I must of taken it the wrong way, and in future if she is rude I must take her somewhere private to tell her and not do it in the office. She was then the life and soul of the party for the rest of the day!!!

I kept quiet for the rest of the day and before I went home she asked for a word in a separate office, I went in and she said she wanted to draw a line under today, that she valued the help and training I'd given her and that she was just stressed. I said we will start again but she again criticised me saying I should always tell her in private if she speaks out of turn. She also said she feels left out if I go outfor a walk at lunchtime with another colleague whom I am friends with outside of work. We don't always go out together at lunch. We work in a medium sized office and I can't understand why she feels left out. Everyone mucks in at work and we all get on. I feel this is just another excuse why everything is not her fault.

She always has to have the last word. Her reaction has just shocked me and I don't think of her as the nice woman I thought she was. She seems childish and selfish, where nothing is her fault and everything is always someone else's fault. She can be quiet a negative person.

I am going to remain professional and help her where needed, if she talks to me I will listen and reply. But I am reluctant to tell her anything about my personal life or engage in a friendship - from now on she is simply a colleague I have to work with. Am I being unreasonable?

I think you have a very insecure and lonely lady there, probably with a very poor life away from work. All you can really do is be as pleasant as possible while protecting yourself from manipulation and if endless chattering is causing a problem your supervisor should talk to her.
Let's face it there will always be people that do not fit in with a particular grouping and if that continues they will move on or be moved on, that is why your supervisor is paid more, to keep office harmony and efficiency. In my business I have had a few disruptive people, rarely do they change even after two or three cautions, however sympathetic you are look after yourself.